Flee

2025-10-08 09:49:37 +08:00
commit 284e764345
99 changed files with 21742 additions and 0 deletions
--- a/Parsing/RegExpException.cs
+++ b/Parsing/RegExpException.cs
@@ -0,0 +1,113 @@
+using System.Text;
+
+
+namespace Flee.Parsing
+{
+    /**
+     * A regular expression exception. This exception is thrown if a
+     * regular expression couldn't be processed (or "compiled")
+     * properly.
+     */
+    internal class RegExpException : Exception
+    {
+        public enum ErrorType
+        {
+
+            /**
+             * The unexpected character error constant. This error is
+             * used when a character was read that didn't match the
+             * allowed set of characters at the given position.
+             */
+            UNEXPECTED_CHARACTER,
+
+            /**
+             * The unterminated pattern error constant. This error is
+             * used when more characters were expected in the pattern.
+             */
+            UNTERMINATED_PATTERN,
+
+            /**
+             * The unsupported special character error constant. This
+             * error is used when special regular expression
+             * characters are used in the pattern, but not supported
+             * in this implementation.
+             */
+            UNSUPPORTED_SPECIAL_CHARACTER,
+
+            /**
+             * The unsupported escape character error constant. This
+             * error is used when an escape character construct is
+             * used in the pattern, but not supported in this
+             * implementation.
+             */
+            UNSUPPORTED_ESCAPE_CHARACTER,
+
+            /**
+             * The invalid repeat count error constant. This error is
+             * used when a repetition count of zero is specified, or
+             * when the minimum exceeds the maximum.
+             */
+            INVALID_REPEAT_COUNT
+        }
+
+        private readonly ErrorType _type;
+        private readonly int _position;
+        private readonly string _pattern;
+
+        public RegExpException(ErrorType type, int pos, string pattern)
+        {
+            this._type = type;
+            this._position = pos;
+            this._pattern = pattern;
+        }
+
+        public override string Message => GetMessage();
+
+        public string GetMessage()
+        {
+            StringBuilder buffer = new StringBuilder();
+
+            // Append error type name
+            switch (_type)
+            {
+                case ErrorType.UNEXPECTED_CHARACTER:
+                    buffer.Append("unexpected character");
+                    break;
+                case ErrorType.UNTERMINATED_PATTERN:
+                    buffer.Append("unterminated pattern");
+                    break;
+                case ErrorType.UNSUPPORTED_SPECIAL_CHARACTER:
+                    buffer.Append("unsupported character");
+                    break;
+                case ErrorType.UNSUPPORTED_ESCAPE_CHARACTER:
+                    buffer.Append("unsupported escape character");
+                    break;
+                case ErrorType.INVALID_REPEAT_COUNT:
+                    buffer.Append("invalid repeat count");
+                    break;
+                default:
+                    buffer.Append("internal error");
+                    break;
+            }
+
+            // Append erroneous character
+            buffer.Append(": ");
+            if (_position < _pattern.Length)
+            {
+                buffer.Append('\'');
+                buffer.Append(_pattern.Substring(_position));
+                buffer.Append('\'');
+            }
+            else
+            {
+                buffer.Append("<end of pattern>");
+            }
+
+            // Append position
+            buffer.Append(" at position ");
+            buffer.Append(_position);
+
+            return buffer.ToString();
+        }
+    }
+}